Former Google and Facebook executives are sounding the alarm about the pervasive power of tech. Will we listen?

One source of angst came close to being 2017’s signature subject: how the internet and the tiny handful of companies that dominate it are affecting both individual minds and the present and future of the planet. The old idea of the online world as a burgeoning utopia looks to have peaked around the time of the Arab spring, and is in retreat.

If you want a sense of how much has changed, picture the president of the US tweeting his latest provocation in the small hours, and consider an array of words and phrases now freighted with meaning: Russia, bots, troll farms, online abuse, fake news, dark money.